/*
 * Copyright (c) 2009, Hamish Morgan. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the University of Sussex nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package locusts.server.behaviours;

import javax.vecmath.Vector2d;
import locusts.common.entities.Actor;

public class Average extends AbstractBehaviourList {

    public  Average(double weight) {
        super(weight);
    }
    @Override
    public Vector2d getSteering(Actor boid) {
        Vector2d[] forces = getForces(boid);
        Vector2d steering = average(forces);
        steering.scale((double) getWeight());
        return steering;
    }

    /**
     * Calculate the mean average vector.
     * 
     * @param vecs
     * @return
     */
    private final Vector2d average(final Vector2d[] vecs) {
        if (vecs == null || vecs.length == 0)
            throw new IllegalArgumentException();

        final Vector2d out = sum(vecs);

        out.scale(1f / vecs.length);

        return out;
    }

    /**
     * Add the vectors int he array together.
     *
     * @param vecs
     * @return
     */
    private final Vector2d sum(final Vector2d[] vecs) {
        if (vecs == null)
            throw new IllegalArgumentException();

        final Vector2d out = new Vector2d();

        for (int i = 0; i < vecs.length; i++)
            out.add(vecs[i]);

        return out;
    }

   
}
